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For 1990-2009 cars only
Makes 🢒 Buick 🢒 1999 🢒 Regal (China) (CNG) 🢒 Restraints 🢒 SIR 🢒 AIR BAG Warning Lamp Circuit Malfunction

Object Number: 369426 Size: SF
SIR Components
SIR Schematics
SIR Caution
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The ignition switch supplies Ignition 1 voltage to the inflatable restraint sensing and diagnostic module (SDM) at terminal A1 using the AIR BAG Fuse. The ignition switch also supplies Ignition 1 voltage to the instrument cluster. The AIR BAG warning lamp is controlled by the SDM via Class 2 serial data. When the ignition switch is first turned to the RUN position, the SDM responds by performing tests on the SIR system and then commanding the AIR BAG warning lamp OFF after it has flashed seven times. If IGNITION 1 is outside of the normal operating voltage range (9 - 16 volts), the AIR BAG warning lamp will come ON solid with no DTCs set.

Diagnostic Aids

The loss of serial data communication between the SDM and the instrument cluster will cause the AIR BAG warning lamp to come ON solid. Refer to Diagnostic System Check - Data Link Communications in Data Link Communications.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. This step checks to see if the AIR BAG warning indicator flashes seven times when the ignition key is turned to the RUN position.

    2.

  2. This step checks to see if the AIR BAG warning indicator is being commanded ON.

    3.

  3. This step checks to see if the ignition voltage to the SDM is more than 9 V.

    4.

  4. This step determines if the ignition voltage to the SDM is more than 16 V or if there is a malfunctioning SDM.

    5.

  5. This step checks to see if the SDM wiring harness connector is corroded or damaged.

    6.

  6. This step determines if there is an open or a high resistance in CKT 1139 or if there is a high resistance in the power feed circuit to the SIR Fuse.

AIR BAG Warning Lamp Circuit Malfunction

Step

Action

Value(s)

Yes

No

1

Was the SIR Diagnostic System check performed?

--

Go to Step 2

Go to SIR Diagnostic System Check

2

Was the Instrument Cluster Diagnostic System Check performed?

--

Go to Step 3

Go to Diagnostic System Check - Instrument Cluster

in Instrument Panel, Gauges and Console

3

  1. Turn the ignition switch to the OFF position.
  2. Observe the AIR BAG warning lamp while turning the ignition switch to the RUN position.

Does the AIR BAG warning lamp flash seven times?

--

Go to Step 5

Go to Step 4

4

Replace the instrument cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gauges and Console.

Is the repair complete?

--

Go to Step 14

--

5

Use the scan tool to request the instrument cluster data list display.

Is the AIR BAG warning lamp being commanded ON?

--

Go to Step 6

Go to Step 4

6

  1. Establish communication with the SDM.
  2. Use the scan tool to request the SIR data list display.

Is the ignition voltage displayed on the scan tool more than the specified value?

9 V

Go to Step 7

Go to Step 8

7

Is the ignition voltage displayed on the scan tool more than the specified value?

16 V

Go to Battery Is Undercharged or Overcharged in Engine Electrical

Go to Step 13

8

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the inflatable restraint sensing and diagnostic Module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .
  3. Inspect the SDM wiring harness connector for corrosion or damaged terminals.

Is the SDM wiring harness connector corroded or damaged?

--

Go to Step 9

Go to Step 10

9

Replace the SDM wiring harness connector. Refer to Wiring Repair .

Is the repair complete?

--

Go to Step 14

--

10

  1. Remove the AIR BAG Fuse.
  2. Disconnect inline connectors C215 and C216.
  3. Use the J 39200 Digital Multimeter (DMM) to measure the resistance between the output side of the AIR BAG Fuse and terminal A1 of the SDM wiring harness connector.

Is the measured resistance within the specified value?

0-2 ohms

Go to Step 12

Go to Step 11

11
  1. Locate an open or a high resistance in CKT 1139.
  2. Repair the open or the high resistance in CKT 1139.

Is the repair complete?

--

Go to Step 14

--

12
  1. Locate a high resistance in the power feed circuit to the AIR BAG Fuse. Refer to Power Distribution Schematics in Wiring Systems.
  2. Repair the high resistance in the power feed circuit to the AIR BAG Fuse.

Is the repair complete?

--

Go to Step 14

--

13

Replace the SDM. Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement .

Is the replacement complete?

--

Go to Step 14

--

14
  1. Reconnect all SIR and instrument cluster components.
  2. Make sure that all components and connectors are properly mounted.

Have all SIR and instrument cluster components been properly reconnected and properly mounted?

--

Go to SIR Diagnostic System Check

--